1. Field of the Invention
The present invention relates to an ink cartridge for a printing machine, such as an inkjet printer, and more particularly, to an ink cartridge having air inflow passageways which are prevented from being clogged with flowing-back ink expanded by movements of the ink cartridge upon carrying the printing machine, an external temperature rise, and so on, or with an inflow of minute dust and so on upon printing.
2. Description of the Related Art
In general, a printing machine prints color images using four different ink colors, such as magenta, cyan, yellow, and black. In order to supply 4 different inks to a printer head of the printing machine upon printing, the printing machine generally uses a color ink cartridge containing the magenta, cyan, and yellow inks, and a mono or black ink cartridge containing black ink.
In FIGS. 1 and 2, a general color ink cartridge 20 for an inkjet printer is schematically illustrated.
The ink cartridge 20 is provided with three ink-containing chambers 60 corresponding to three colors of magenta, cyan, and yellow. Each of the ink-containing chambers 60 is divided into an ink chamber 60a as an ink reservoir, and a foam chamber 60b defined by a wall 83 having a communicating opening 83a on a lower portion thereof.
The foam chamber 60b is filled with a porous member 84, and a filter 71 is disposed between the porous member 84 and an ink supply port 28.
On a cover member 22 of the ink cartridge 20 are formed holes 73, 75 and a rib portion having a plurality of protrusions 72, which are spaced apart in certain intervals. The protrusions 72 provide a predetermined space between the porous member 84 and the cover member 22.
Further, a part of the ink supply port 28 is formed to protrude inside the foam chamber 60b. 
As shown in FIG. 3, the cover member 22 has ink injection openings 74, air inflow openings 76, air inflow grooves 80 opened to an ambient atmosphere, and snake-shaped grooves 78 connecting the air inflow openings 76 to the air inflow grooves 80.
As shown in FIG. 1, the air inflow grooves 80 are sealed with a film 82 prior to use of the ink cartridge 20 and opened to an external atmosphere when the film 82 is eliminated for use. The film 82 has a tongue portion 82a for the film 82 to be easily removed from the cover member 22 when the cartridge 20 is used.
Operations of the ink cartridge 20 constructed with the above structure are described. First, prior to the use of the ink cartridge 20, the tongue portion 82a of the film 82 is pulled out and eliminated to open the air inflow grooves 80. As a result, the ink-containing chambers 60 are opened to the external atmosphere through the snake-shaped grooves 78 and the air inflow grooves 80.
Thereafter, the ink cartridge 20 is mounted on a cartridge holder (not shown) the inkjet a printer using guides 36 and fluid-communicates with a printer head (not shown). When printing starts, a negative pressure produced in the printer head causes the ink stored in the porous member 84 to be pulled toward an inside of the ink-containing chambers 60. At this time, the ink-containing chambers 60 are opened to the external atmosphere through the air inflow openings 76, snake-shaped grooves 78, and air inflow grooves 80 to maintain a constant negative pressure, so that air, dust, and the like are removed from the ink by the filter 71, and only pure ink is supplied to the printer head.
However, since the ink cartridge 20 constructed with the above structure has the fine, zigzag, and lengthy snake-shaped grooves 78 for an inflow of external air to maintain the negative pressure inside the ink cartridge 20, ink expansion caused by movements of the ink cartridge 20 upon movements of the inkjet printer or by an ambient temperature rise may cause a part or an entire part of the snake-shaped grooves 78 to be clogged with flowing-back ink.
Particularly, in a case that foreign minute dust flowing into the snake-shaped grooves 78 by the negative pressure formed by the printer head is combined and dried with the flowing-back ink, the snake-shaped grooves 78 may not provide an air inflow to the air inflow grooves 80.
As described above, in the case that the part or the entire part of the snake-shaped grooves 78 is clogged with the dried ink and/or dust and the like, the negative pressure is not produced inside the ink-containing chambers 60 even though the negative pressure for injecting the ink is produced in the printer head, so that the ink is not smoothly supplied, thereby reducing an image quality or disabling a printing process.